The present invention relates to tissue sampling devices associated with biopsy needles, and in particular, to an automatic tissue sampling apparatus for utilizing two-piece biopsy needle systems for facilitating the retrieval of a tissue sample for testing.
A typical biopsy needle system utilized in obtaining tissue samples is composed of two parts, a first inner needle and a second outer needle. The first inner needle consists of a substantially solid shaft, having a first handle disposed at one end. A cutting point, to facilitate insertion of the needle into the tissue to be sampled, is located at the other end of the shaft, opposite to the position of the handle. Positioned proximate to the cutting point, is a tissue holding region, which is in the form of a cut-out region or flat in the otherwise substantially cylindrical shaft.
The second outer needle is typically hollow. At one end a second handle is disposed. The hollow passageway extends through the second handle, to enable the solid shaft of the first inner needle to be inserted into the passageway and into and through the entire hollow shaft of the second outer needle.
The shaft of the first inner solid needle is typically greater in length than the entire second outer hollow needle structure. When the first and second handles are placed in a particularly spaced co-axial configuration, the hollow shaft of the second outer needle covers the tissue holding region of the first inner needle. The tissue holding region may be exposed by projecting the first inner needle further into the second outer needle, bringing the first and second handles closer together.
To obtain a tissue sample, the biopsy needle is typically inserted into a patient, into the specific tissue to be sampled, at the desired cell mass to be investigated, with the first inner and second outer needles relatively positioned in the first described configuration, so that the tissue holding region is covered. The tissue holding region is then exposed, by the operator holding the second handle of the second outer needle stable while projecting the first inner needle forward a short distance along its sharp pointed region--until a portion of the tissue being tested surrounds the flat cut-out of the tissue holding region.
The second outer needle, which also has a sharp, though hollow, point disposed at the end of the hollow shaft opposite the second handle, is then moved forward, relative to the now-stabilized first inner needle--to cut off the tissue sample from the rest of the tissue, and cover the tissue sample about the flat cut-out of the tissue holding region. The angled cutting point of the second outer needle serves to sever the tissue sample. The first inner and second outer needles are typically maintained in a particular angular concentric orientation with respect to one another, prior to insertion, so as to maintain the forwardmost portion of the second outer needle point centered when positioned over the flat, cut-out region of the first inner needle.
After the tissue is severed and confined between the first inner and second outer needles, the inner and outer needles will be brought back to the same relative positions they occupied immediately prior to initial insertion of the biopsy needle system into the patient. To prevent loss or contamination of the tissue sample, the first inner and second outer needles are typically removed from the patient in this tissue-isolating configuration.
As the configuration of the first inner and second outer needles, utilized for initial insertion, and final removal from the patient, requires that the first and second handles be spaced apart in a particular configuration, the manual manipulation of such a biopsy needle system requires considerable dexterity, concentration and skill on the part of the operator. The concentration necessary to maintain the proper spacing may detract from the concentration necessary to make insertion and removal of the biopsy needle as painless as possible for the patient. Accordingly, it is desirable to provide a form of automatic tissue sampling apparatus, which accomplishes some, if not all of the handling steps just described--so that the operator may be concerned with the crucial initial step of insertion and final step of removal, of the biopsy needle; to reduce the amount of discomfort to the patient, to improve the quality of the results of the tissue sampling procedure, and to enhance the successful repeatability of the procedure, from one patient to the next.
Examples of prior art automatic tissue sampling apparatus include those disclosed in PCT application No. PCT/SE83/00112, Swedish Patent No. 8600755, U.S. Pat. No. 4,699,154, issued to Lindgren, EPO Application No. 0 318 447 and Swiss Patent No. 483 829.
In the PCT application, an automatic tissue sampling apparatus is disclosed, in which the first inner needle of the biopsy needle is propelled forward by a pressure plate which is driven by a compressed spring, and the second outer needle is propelled by a movable slide which receives the second handle of the second outer needle. The movable slide for holding the second outer needle is also propelled by a compressed spring. In order to prepare the apparatus for use, each of the springs and respective slides must be cocked separately, either manually or through the use of a specially shaped tool. The slide for the outer handle is held in place by a catch which is configured to be released upon contact with a projection arranged upon the slide for the first handle of the first inner needle. The pressure plate for the first handle of the first inner needle is in turn retained in its cocked position by a trigger which is actuatable by the operator. While it is possible to cock each of the springs, with the biopsy needle already in place, it is contemplated that such cocking will take place well prior to loading of the needle.
In operation then, once the springs have been cocked and the biopsy needle has been loaded, the operator inserts the needle into the tissue to be sampled, as previously described. He or she may then depress the trigger which releases the spring for propelling the first inner needle. As the first inner needle is moved forward, the pressure plate releases the retaining mechanism which has been previously holding the movable slide for the second handle of the second outer needle. The second outer needle is thus moved forward shortly after the first inner needle, completing the sampling movement. The trigger in the apparatus is biased by a spring into position to retain the compressed spring for the first inner needle slide, and is configured to provide increasing resistance to depression, up until a predetermined position, at which point, the resistance is sharply increased and further depression results in the immediate release of the compressed spring. No means are provided for preventing inadvertent actuation of the automatic tissue sampling apparatus. Due to the inherent hazardous nature of the extremely sharp points of the biopsy needle and the power of the springloaded mechanism, it is desirable, therefore, to provide a tissue sampling apparatus which has an automatically engaging safety mechanism, which must be consciously overcome before the tissue sampling apparatus may be actuated. In addition, it may be often awkward and/or difficult to manually overcome the force of the uncompressed springs which drive the movable slides. Accordingly, it would be desirable to provide an automatic tissue sampling apparatus which may be readily prepared for use, immediately before insertion, without the need for extreme physical exertion or the use of awkward and/or specially configured tools.
The tissue sampling device embodied in U.S. Pat. No. 4,699,154 to Lindgren discloses a housing in which two slides are mounted for longitudinal movement, the slides being configured to receive the first and second handles of the first inner and second outer needles, respectively. Each of the slides is propelled by a pair of compressed springs. The rearward slide, for propelling the handle of the first inner needle, is propelled by springs which bear against a rear wall of the housing. The slide for the handle of the second outer needle is propelled by compressed springs which bear against a fixed, transversely-extending wall arranged in the housing between the forward and rear slides. Both of the slides are arranged to have a guide member extending through them. A drawbolt is operably associated with each of the slides for limited axial movement relative thereto, such that when the drawbolt is pulled backward, both of the slides are simultaneously drawn against the bias of the respective springs, to a cocking position. When the cocking position is reached, retaining members associated with each of the slides engage the respective slides to retain them in their cocked positions.
In a manner similar to that discussed with regard to the PCT application, an external triggering mechanism is provided, which is actuatable by the operator to release the retaining mechanism for the slide for the first inner needle. Once the slide for the first inner needle has been propelled forward, a predetermined distance, a projection on the first slide releases the retaining mechanism for the slide for the handle of the second outer needle; enabling it to be propelled forward by its respective springs.
One possible drawback to the tissue sampling apparatus of the Lindgren '154 patent is that it is configured so that both sets of springs are compressed, and the slides brought into their retained positions by a single pulling motion upon the drawbolt. Accordingly, the combined strengths of all of the springs must be overcome in order to cock the mechanism. Due to the substantial power stored in the springs which is necessary for the rapid operation of the tissue sampling apparatus, it may be difficult for certain operators to rapidly and easily operate the cocking mechanism. Accordingly, it would be desirable to provide an automatic tissue sampling apparatus with a built-in cocking mechanism which is readily and easily operated, and which does not require substantial strength or effort in order to arm the apparatus.
The tissue sampling device of the Lindgren '154 patent is also provided with a safety mechanism, for precluding inadvertent actuation. However, the safety mechanism is configured such that it must be positively engaged by the operator, in order to place the tissue sampling apparatus into condition that it cannot be accidentally fired. Accordingly, the effectiveness of the safety device is dependent upon the operator remembering to set the safety. It would be more desirable to provide an automatic tissue sampling apparatus which is configured with a safety device which engages automatically upon the cocking of the apparatus, and is thereby not dependent upon the operator's remembering to engage the safety. Rather, it would be desirable to configure the safety device so the operator must affirmatively disengage the safety before the tissue sampling apparatus can be actuated.
Swiss Patent No. 483 829 discloses a "gun"-shaped automatic tissue sampling apparatus, in which the springs are cocked by direct pulling force, and so suffers from the same potential drawback of requiring substantial difficulty and effort to arm the device.
EPO Application No. 0 318 447 discloses a purportedly disposable automatic tissue sampling apparatus, in which the springs for the slides for the first inner and second outer needles are simultaneously cocked by rotating an outer sleeve backward, against the force of both springs. Tabs on the slides ride on cam surfaces to force the slides backward against the springs requiring substantial effort to operate.
In addition to the foregoing, it is well known that often during tissue sampling procedures, the quality and/or quantity of the tissue being sampled may vary from procedure to procedure. Accordingly, it is desirable to provide a means for permitting inspection of the tissue sample, without removing the biopsy needle components from the tissue sampling apparatus. In that way, should the size or quality of the sample be inadequate, the biopsy needle may be reinserted into the very same patient for another attempt at obtaining a suitable sample. Such a sample inspection procedure would also permit access to the sample for subsequent deposit of same onto a microscope slide or other sample holding apparatus for further processing of the tissue sample.
Such prior art tissue sampling apparatus such as those disclosed in the PCT application and in the Lindgren '154 patent are known to be large, relatively heavy and complicated devices, which are also relatively costly.
It is thus an object of the present invention is to provide an improved automatic tissue sampling apparatus which is easy to load and bring into readiness for use, without undo exertion and/or complicated manipulation of its components; while providing a facilitated, positive locking, tissue sample inspection capability.
It is a further object of the invention to provide an automatic tissue sampling apparatus which is provided with an automatically engaging safety device, which does not rely upon the operator for its effectiveness and which must be affirmatively disengaged before the tissue sampling apparatus may be actuated.
The present invention seeks, as another goal, the provision of an automatic tissue sampling apparatus which is less complicated and therefore easier and less expensive to construct, and which has a lighter construction for greater ease of operation and manipulation.
Yet another goal of the invention is to provide an automatic tissue sampling apparatus which is provided with various internal shock and sound absorbing means so as to render the apparatus quieter and less jarring in operation, so as to decrease the actual and/or perceived discomfort of the patient during the tissue sampling procedure; while ensuring better practitioner accuracy during the procedure.
These and other objects and goals of the invention will become apparent and light of the present specification, drawings and claims.